Many people would argue that it would have been a fine thing if HSBC had recruited an outside chairman years ago – the board might have avoided the group-think that seemed to be a factor behind the awful decision to pay £9bn for a US sub-prime lender in 2003.

Sir Keith Whitson, who retired from HSBC in the same year, is not one. In a letter to today's Daily Telegraph, the former chief executive said it would be "extremely demotivating" to the number of "exceptionally capable executives serving on the HSBC board" if an outsider was chosen.

Whitson may or not be right about the wisdom of keeping the job in the family. But you suspect he's spot on in describing the internal reaction if HSBC abandons its tradition of promoting from within. The crew would not be happy.

This a case of "damned if you do, damned if you don't" for HSBC, since some shareholders would be enraged if Michael Geoghegan, the current chief executive, was shoved upstairs. John Thornton is the bookies' favourite on the grounds that he's the compromise candidate – he's an ex-Goldman Sachs man but an HSBC non-executive. But what if Thornton doesn't want the job? Sit back and wait for the fireworks.